Pure Paladin, 1 to 12. Click exactly what's written. Explorer difficulty, front line, with a Warlock blasting from behind.
From level 5 one Attack hits twice on its own. Nothing extra to click.
If you break it you lose your Oath powers. A knight shows up at camp who can restore them for gold. If you'd rather not care at all, switch to Oathbreaker. That's a different build, so ask before switching.
Paladins pick which spells to have ready. Fill your slots from the top of this list and never touch it again. New ones unlock as you level.